This invention relates to farm implements that are pulled behind a tractor for tilling, planting or cultivating.
Farm implements include seed planters, cultivators, tillers and other implements. Typically, these implements have a number of individual row units spaced along a trailing bar on the implement, each row unit operating in a row or furrow being planted or cultivated.
It is desired to provide down pressure in such units to keep them from bouncing or leaving a furrow. One method of creating down pressure uses tension springs to create a load between two links. As the links move in parallel, the spring begins to stretch. The loading of the spring tends to pull on the links to apply pressure to keep a working tool on the row unit in the ground.
Compression springs can also be used to create down pressure. These springs are fixed, so that as the row unit moves upwardly from the ground or furrow, the spring is compressed or loaded to provide a reactionary force towards the ground.
Air bags can also be used to provide down pressure. The air bags can be inflated to a selected pressure. The pressure in the bag tends to keep the row unit in the ground while allowing dampening of upward movements.
Another example of a down pressure row unit is illustrated in Prairie, U.S. Pat. No. 6,454,019, assigned to the assignee herein, where a non-spring, elastomeric torsion element is used to provide a down pressure bias pressing the row unit against the ground. The bias is adjusted with a threaded stem and a knob to be adjusted by hand. The threaded member is subject to the need for lubrication when exposed to the environment over periods of time. This adjustment also lacks a visual indicator of discrete adjustments. The down pressure bias cannot be completely disabled in a convenient fashion.
It is desired to provide an improved torsional down pressure row unit providing discrete adjustments including total disablement and lower maintenance requirements.